Lack of hepcidin expression attenuates steatosis and causes fibrosis in the liver

AIM: To investigate the role of key iron-regulatory protein, hepcidin in non-alcoholic fatty liver disease(NAFLD). METHODS: Hepcidin(Hamp1) knockout and floxed control mice were administered a high fat and high sucrose(HFS) or a regular control diet for 3 or 7 mo. Steatosis, triglycerides, fibrosis, protein and gene expression in mice livers were determined by histological and biochemical techniques, western blotting and realtime polymerase chain reaction. RESULTS: Knockout mice exhibited hepatic iron accumulation. Despite similar weight gains, HFS feeding induced hepatomegaly in floxed, but not knockout, mice. The livers of floxed mice exhibited higher levels of steatosis, triglycerides and c-Jun N-terminal kinase(JNK) phosphorylation than knockout mice. In contrast, a significant increase in fibrosis was observed in knockout mice livers within 3 mo of HFS administration. The hepatic gene expression levels of sterol regulatoryelement-binding protein-1c and fat-specific protein-27, but not peroxisome proliferator-activated receptoralpha or microsomal triglyceride transfer protein, were attenuated in HFS-fed knockout mice. Knockout mice fed with regular diet displayed increased carnitine palmitoyltransferase-1a and phosphoenolpyruvate carboxykinase-1 but decreased glucose-6-phosphatase expression in the liver. In summary, attenuated steatosis correlated with decreased expression of lipogenic and lipid storage genes, and JNK phosphorylation. Deletion of Hamp1 alleles per se modulated hepatic expression of beta-oxidation and gluconeogenic genes. CONCLUSION: Lack of hepcidin expression inhibits hepatic lipid accumulation and induces early development of fibrosis following high fat intake. Hepcidin and iron may play a role in the regulation of metabolic pathways in the liver, which has implications for NAFLD pathogenesis.     

Bezafibrate对大鼠高脂血症和脂肪肝形成的影响

目的探讨以降低甘油三酯为主的血脂调整药对高脂血症脂肪肝的防治作用。方法观察Ｂｅｚａｆｉｂｒａｔｅ对高脂饮食诱发Ｗｉｓｔａｒ大鼠高脂血症和脂肪肝形成的影响（治疗组,ｎ＝８）,并设模型组和正常饮食组作对照。结果与正常组相比,模型组血脂和肝匀浆脂肪含量均显著升高,肝组织学呈中至重度脂肪变。与模型组相比,治疗组血清甘油三酯和总胆固醇显著下降,但血清转氨酶和肝匀浆脂质含量却呈升高趋势,肝脏病理学变化与模型组基本相近。结论Ｂｅｚａｆｉｂｒａｔｅ虽可显著降低高脂饮食诱发的高脂血症,但对肝内脂肪沉积并无防治作用。     

Reduction of hepatosteatosis and lipid levels by an adipose differentiation-related protein antisense oligonucleotide

BACKGROUND & AIMS: Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive triglyceride accumulation in hepatocytes. Expression of the lipid droplet protein adipose differentiation-related protein (ADRP) is increased in NAFLD, but whether this is causally linked to hepatic lipid metabolism is unclear. We postulated that a reduction in ADRP would ameliorate hepatic steatosis and improve insulin action. METHODS: Leptin deficient Lep(ob/ob) and diet-induced obese (DIO) mice were treated with antisense oligonucleotide (ASO) against ADRP, and effects on hepatic and serum lipids and glucose homeostasis were examined. RESULTS: ADRP ASO specifically decreased ADRP mRNA and protein levels in the livers of Lep(ob/ob) and DIO mice, without altering the levels of other lipid droplet proteins, that is, S3-12 and TIP47. ADRP ASO suppressed expression of lipogenic genes, reduced liver triglyceride content without affecting cholesterol, attenuated triglyceride secretion, and decreased serum triglyceride and alanine aminotransaminase levels. The reduction in hepatic steatosis by ADRP ASO was associated with improvement in glucose homeostasis in both Lep(ob/ob) and DIO mice. CONCLUSIONS: This study demonstrates a crucial role for the lipid droplet protein ADRP in regulation of lipid metabolism. Reduction in hepatic ADRP level using an antisense oligonucleotide reverses hepatic steatosis, hypertriglyceridemia, and insulin resistance in obese mice, suggesting that ADRP may be targeted for the treatment of NAFLD and associated lipid and glucose abnormalities.     

Study on lipid absorption in uraemia

While the occurrence of morphological and functional small intestinal alterations in chronic uraemia is well established, analyses of intestinal lipid utilization are rare. In the present study faecal fat excretion in chronically uraemic humans and rats and the reesterification of a long-chain fatty acid in the mucosa of the small intestine of uraemic rats were investigated. -Reesterification of 14C-palmitic acid in the intestinal mucosa of rats with chronic uraemia produced by 5/6-nephrectomy (BUN 37.8 +/- 12.8 mg/100 ml, serum creatinine 3.0 +/- 0.44 mg/100 ml) was found to be significantly lower (374.2 +/- 166.8 mumol/mg protein x h) than in controls (604.9 +/- 274.2 mumol/mg protein x h) pointing to a disturbance of the intracellular process of absorption of long-chain fatty acids. However, the mean daily fat excretion in the faeces of chronically uraemic rats fed a diet with normal (4.2 per cent) or relatively high fat content (10 and 15 per cent) was not increased. In 20 patients with chronic renal insufficiency (BUN 75.9 +/- 35.9 mg/100 ml, serum creatinine 7.5 +/- 2.8 mg/100 ml) the faecal fat excretion was within the normal range (4.2 +/- 1.2 g/day). These results indicate a sufficient compensation of the impaired intestinal reesterification of fatty acids by the large functional reserve of the small intestine.     

Alcohol-induced liver injury after jejunoileal bypass operation in rats

The objective of this study was to investigate whether alcohol administration exerts a synergistic effect on jejunoileal bypass-induced liver dysfunction in rats. Male Wistar rats were subjected to 90% jejunoileal bypass or sham operation. For 10 weeks, subgroups were pair-fed either an alcohol-containing (36% of total calories) liquid diet or a liquid diet where alcohol was replaced isocalorically by starch. Alcohol feeding in rats with jejunoileal bypass increased hepatic triglyceride content about 6-fold as compared with bypassed rats receiving control diet. Neither jejunoileal bypass nor alcohol feeding led to significant changes in hepatic DNA and protein contents. Alcohol feeding increased cytochrome P-450 levels both in operated and in sham-operated rats. The administration of alcohol-containing diet decreased the activity of succinic dehydrogenase, the decrease being distinctly more pronounced in rats with jejunoileal bypass than in the sham-operated controls. Light microscopy revealed no significant morphological alterations in liver sections of rats fed the control diet after jejunoileal bypass or of rats receiving either the alcohol-containing diet or the control diet after sham operation. Alcohol feeding in bypassed rats, however, produced marked diffuse accumulation of fat, and regularly led to other histological abnormalities in the liver. These abnormalities included ballooning of hepatocytes and disarray of the trabecular structure of the liver lobule, hyalin inclusions resembling megamitochondria, single-cell necrosis and focal clustering of necrosis, increased number of mitotic figures, and infiltrates with inflammatory cells. The histological lesions of the liver of bypassed rats receiving alcohol exhibited no obvious zonal distribution. The results demonstrate that alcohol feeding to rats subjected to jejunoileal bypass leads to marked liver injury which mimics, at least in part, that of alcohol-induced liver disease in man. Rats subjected to jejunoileal bypass may, therefore, provide a new model for the study of alcoholic liver disease.     

Effect of chronic alcohol administration on the exocrine pancreas after jejunoileal bypass in the rat

To determine whether intestinal bypass operation and alcohol administration exerted a synergistic effect on pancreatic enzyme composition and morphology, adult rats were submitted either to a sham-operation or to a 90 per cent jejunoileal bypass. Two weeks after the operation, the rats received a 15 per cent solution of ethanol in drinking fluid during a period of four weeks while controls received water. In sham-operated animals, alcohol had no effect on pancreatic weight or its total content in protein and amylase. The general structural and ultrastructural aspect remained unchanged except for the presence of a few mixed acinar-islet cells. Bypass operation alone induced a significant decrease in amylase content while the population of zymogen granules was reduced. Parallely, lipid droplets deposited within acinar cells. Alcohol administered in bypassed animals exerted a synergistic effect on fat accumulation in pancreatic acinar cells but had no effect on other biochemical and morphological parameters.     

甘氨酸对高脂饮食诱导小鼠高脂血症的保护作用

目的研究甘氨酸(Gly)降低高脂血症小鼠血脂的作用。方法将40只小鼠随机分为对照组、高脂组、小剂量和大剂量甘氨酸处理组,在不同处理2周后,取血测定小鼠血酯水平、肝组织丙二醛(MDA)和超氧化物歧化酶(SOD)活性,及观察肝组织病理形态学表现。结果与对照组比,高脂饮食小鼠TC、LDL、HDL-C、MDA含量明显增高(P0.05),SOD活性下降(P0.05);与高脂血症动物比,甘氨酸处理小鼠血TC、LDL明显降低(P0.01),MDA含量下降(P0.05),SOD活性升高(P0.05);高脂血症小鼠肝组织可见弥漫性脂肪变性,而甘氨酸处理动物肝细胞内脂滴小且少。结论甘氨酸可通过调节血脂代谢增强抗氧化能力,从而能防治高脂血症所致的肝脂肪变性。     

肝内脂肪和脂质过氧化与肝纤维化关系的实验研究

为探讨脂肪肝与肝纤维化的关系及其机制，以高脂饮食和（或）酒精诱发Ｗｉｓ－ｔａｒ大鼠脂肪肝模型，观察造模３个月和６个月时肝脏病理学变化，分析造模６个月时肝内甘油三酯（ＴＧ）、丙二醛（ＭＤＡ）含量与羟脯氨酸（Ｈｙｐ）含量及α－平滑肌肌动蛋白（α－ＳＭＡ）阳性细胞数间的相关性。结果：与低脂饮食组相比，高脂饮食组ＴＧ显著升高，但ＭＤＡ和Ｈｙｐ及α－ＳＭＡ阳性细胞数基本正常；低脂饮食酒精组ＴＧ、ＭＤＡ、Ｈｙｐ和α－ＳＭＡ阳性细胞数均显著增多，高脂饮食酒精组以上改变更加明显，各指标与其他３组相比差异均有显著性；各组ＴＧ含量与α－ＳＭＡ阳性细胞数均不相关，ＴＧ与Ｈｙｐ仅在低脂饮食酒精组呈正相关，而ＭＤＡ与Ｈｙｐ和α－ＳＭＡ细胞数间在低脂饮食酒精组和高脂饮食酒精组均呈正相关。结果提示肝内脂肪本身与贮脂细胞激活和肝纤维化形成间并无直接关系，但其可通过增强肝脏脂质过氧化反应促进肝纤维化的发生和发展。     

Involvement of remnant spleen volume on the progression of steatohepatitis in diet-induced obese rats after a splenectomy

Aim: This study investigated the correlation between remnant spleen volume after splenectomy (SPX) and the degree of hepatic steatosis and/or inflammation. Methods: Male Sprague–Dawley rats were fed HF food and divided into three groups: sham‐operation (Sham) group, a hemisplenectomy (H‐SPX) group, and a total‐splenectomy (T‐SPX) group. Serum was collected and livers removed 12 weeks after surgery. We measured serum lipid markers and evaluated liver changes by comparing the three groups. Additionally, we examined liver changes 24 weeks after SPX. Results: Serum triglyceride and free fatty acid levels after SPX were higher than those of sham controls, and a significant difference was found between T‐SPX and the other groups (P < 0.05 for each). Increased intrahepatic fat accumulation was shown in SPX rats along with lower residual spleen volume; this fat accumulation after SPX was accelerated in rats at 24 weeks. Additionally, liver inflammatory changes, including an increase in the Kupffer cell population and pro‐inflammatory cytokine production, as well as a high level of oxidative stress, were observed in the liver sections from SPX rats, which correlated significantly with less volume of the residual spleen. Also, an increase in pro‐inflammatory cytokine content and a decrease in anti‐inflammatory cytokine content were shown in the residual spleen from H‐SPX rats, as compared to those of sham controls (P < 0.05 for each). Conclusion: These results indicate the importance of preserving splenic tissue. This residual spleen may play an important role in preventing the progression from diet‐induced hepatic steatosis to steatohepatitis.     

蛋白酪氨酸磷酸酶1B在肥胖大鼠下丘脑的表达

目的观察高脂饲料诱导的肥胖大鼠下丘脑蛋白酪氨酸磷酸酶1B（PTP-1B）的表达。方法SD大鼠20只随机分为正常饲料组和高脂饲料组喂养8周。测定大鼠Fins、BG、TG、TC、瘦素、副睾脂肪垫重量、PTP-1B活性;观察肝脏形态学改变;蛋白印迹法检测下丘脑组织中PTP-1B蛋白含量。结果（1）高脂组胰岛素敏感性降低,出现瘦素抵抗和肝脏脂肪变性;（2）高脂组大鼠下丘脑PTP-1B蛋白表达和活性增加。结论高脂饲料可诱导大鼠下丘脑PTP-1B蛋白表达和活性升高,这可能是肥胖引发下丘脑产生胰岛素抵抗和瘦素抵抗的机制之一。     

Effects of iron overload in a rat nutritional model of non-alcoholic fatty liver disease.

BACKGROUND/AIMS: This study sought to determine whether excess hepatic iron potentiates liver injury in the methionine choline-deficient (MCD) model of non-alcoholic fatty liver disease (NAFLD). METHODS: Iron-loaded rats were fed either MCD or control diets [MCD diet plus choline bitartrate (2 g/kg) and DL-methionine (3 g/kg)] for 4 and 12 weeks, after which liver pathology, hepatic iron, triglyceride, lipid peroxidation products and hydroxyproline (HYP) levels and serum alanine aminotransferase (ALT) levels were evaluated. RESULTS: Iron supplementation in MCD animals resulted in histologic evidence of hepatic iron overload at 4 and 12 weeks and a 14-fold increase in hepatic iron concentration at 12 weeks (P < 0.001). Iron supplementation in these animals was associated with increased lobular necroinflammation at 4 weeks (P < 0.02) and decreased hepatic steatosis (P < 0.01), hepatic triglyceride levels (P < 0.01), hepatic-conjugated dienes (CD; P < 0.02) and serum ALT levels (P < 0.002) at 12 weeks. Reduced hepatic steatosis (P < 0.005) and CD (P < 0.01) were apparent by 4 weeks. Iron supplementation was associated with a trend towards increased perivenular fibrosis not hepatic HYP content. CONCLUSION: Hepatic iron overload in the MCD model of NAFLD is associated with decreased hepatic lipid, decreased early lipid peroxidation products, increased necroinflammation and a trend towards increased perivenular fibrosis.     

Ezetimibe decreases SREBP-1c expression in liver and reverses hepatic insulin resistance in mice fed a high-fat diet

Ezetimibe inhibits intestinal cholesterol absorption, thereby reducing serum cholesterol. Recent studies suggest that ezetimibe affects liver steatosis and insulin resistance. We investigated the impact of ezetimibe on insulin sensitivity and glucose metabolism in C57BL/6 mice. We analyzed 4 mouse groups fed the following diets: normal chow (4% fat) for 12 weeks, normal chow for 10 weeks followed by normal chow plus ezetimibe for 2 weeks, high-fat chow (32% fat) for 12 weeks, and high-fat chow for 10 weeks followed by high-fat chow plus ezetimibe for 2 weeks. In the normal chow + ezetimibe group, ezetimibe had no impact on body weight, fat mass, lipid metabolism, liver steatosis, glucose tolerance, or insulin sensitivity. In the high-fat chow + ezetimibe group, ezetimibe had no impact on body weight or fat mass but significantly decreased serum low-density lipoprotein cholesterol, triglyceride, and glutamate pyruvate transaminase levels; liver weight; hepatic triglyceride content; and hepatic cholesterol content and increased the hepatic total bile acid content. In association with increases in IRS-2 and Akt phosphorylation, ezetimibe ameliorated hepatic insulin resistance in the high-fat chow + ezetimibe group, but had no effect on insulin sensitivity in primary cultured hepatocytes. A DNA microarray and Taqman polymerase chain reaction revealed that ezetimibe up-regulated hepatic SREBP2 and SHP expression and down-regulated hepatic SREBP-1c expression. SHP silencing mainly in the liver worsened insulin resistance, and ezetimibe protected against insulin resistance induced by down-regulation of SHP. Ezetimibe down-regulated SREBP-1c in the liver and reversed hepatic insulin resistance in mice fed a high-fat diet.     

Glucagon-like peptide-1 analogue prevents nonalcoholic steatohepatitis in non-obese mice

AIM: To investigate whether a glucagon-like peptide-1(GLP-1) analogue inhibits nonalcoholic steatohepatitis(NASH), which is being increasingly recognized in Asia, in non-obese mice. METHODS: A methionine-choline-deficient diet(MCD) along with exendin-4(20 μg/kg per day, ip), a GLP-1 analogue, or saline was administered to male db/db mice(non-obese NASH model). Four or eight weeks after commencement of the diet, the mice were sacrificed and their livers were excised. The excised livers were examined by histochemistry for evidence of hepatic steatosis and inflammation. Hepatic triglyceride(TG) and free fatty acid(FFA) content was measured, and the expression of hepatic fat metabolism- and inflammation-related genes was evaluated. Oxidative stress-related parameters and macrophage recruitment were also examined using immunohistochemistry.RESULTS: Four weeks of MCD feeding induced hepatic steatosis and inflammation and increased the hepatic TG and FFA content. The expression of fattyacid transport protein 4(FATP4), a hepatic FFA influxrelated gene; macrophage recruitment; and the level of malondialdehyde(MDA), an oxidative stress marker, were significantly augmented by a 4-wk MCD. The levels of hepatic sterol regulatory element-binding protein-1c(SREBP-1c) m RNA(lipogenesis-related gene) and acyl-coenzyme A oxidase 1(ACOX1) m RNA(β-oxidation-related gene) had decreased at 4 wk and further decreased at 8 wk. However, the level of microsomal triglyceride transfer protein m RNA(a lipid excretion-related gene) remained unchanged. The administration of exendin-4 significantly attenuated the MCD-induced increase in hepatic steatosis, hepatic TG and FFA content, and FATP4 expression as well as the MCD-induced augmentation of hepatic inflammation, macrophage recruitment, and MDA levels. Additionally, it further decreased the hepatic SREBP-1c level and alleviated the MCD-mediated inhibition of the ACOX1 m RNA level. CONCLUSION: These results suggest that GLP-1 inhibits hepatic steatosis and inflammation through the inhibition of hepatic FFA influx and oxidative stress in a non-obese NASH model.     

Altered hepatic triglyceride content after partial hepatectomy without impaired liver regeneration in multiple murine genetic models

Liver regeneration is impaired following partial hepatectomy (PH) in mice with genetic obesity and hepatic steatosis and also in wild-type mice fed a high-fat diet. These findings contrast with other data showing that liver regeneration is impaired in mice in which hepatic lipid accumulation is suppressed by either pharmacologic leptin administration or by disrupted glucocorticoid signaling. These latter findings suggest that hepatic steatosis may actually be required for normal liver regeneration. We have reexamined this relationship using several murine models of altered hepatic lipid metabolism. Liver fatty acid (FA) binding protein knockout mice manifested reduced hepatic triglyceride (TG) content compared to controls, with no effect on liver regeneration or hepatocyte proliferation. Examination of early adipogenic messenger RNAs revealed comparable induction in liver from both genotypes despite reduced hepatic steatosis. Following PH, hepatic TG was reduced in intestine-specific microsomal TG transfer protein deleter mice, which fail to absorb dietary fat, increased in peroxisome proliferator activated receptor alpha knockout mice, which exhibit defective FA oxidation, and unchanged (from wild-type mice) in liver-specific FA synthase knockout mice in which endogenous hepatic FA synthesis is impaired. Hepatic TG increased in the regenerating liver in all models, even in animals in which lipid accumulation is genetically constrained. However, in no model -- and over a >90-fold range of hepatic TG content -- was liver regeneration significantly impaired following PH. CONCLUSION: Although hepatic TG content is widely variable and increases during liver regeneration, alterations in neither exogenous or endogenous lipid metabolic pathways, demonstrated to promote or diminish hepatic steatosis, influence hepatocyte proliferation.     

Spontaneously hypertensive rats develop pronounced hepatic steatosis induced by choline-deficient diet: Evidence for hypertension as a potential enhancer in non-alcoholic steatohepatitis

Aim: Patients with non‐alcoholic steatohepatitis (NASH) frequently have many co‐morbidities including essential hypertension, which is reported to increase vascular production of reactive oxygen species (ROS) and alter the hepatic anti‐oxidant defense system. Since ROS play a role in the pathogenesis of NASH, it is hypothesized that hypertension modulates the hepatic oxidative status and influences the development of NASH. The aim of this study was to investigate the potential effects of hypertension on the progression of NASH. Methods: Spontaneously hypertensive rats (SHR) and Wistar‐Kyoto (WKY) rats as normotensive controls were fed choline‐deficient (CD) diet for 5 weeks. Histological changes, messenger RNA (mRNA) expression and thiobarbituric acid reactive substances (TBARS) levels in the liver were assessed in each group. Results: Choline‐deficient diet led to pronounced hepatic steatosis in SHR with an 8‐fold increase of the hepatic triglyceride content, while there was no significant increase in WKY. These changes in SHR were associated with significant reduction in the expression of mRNA for peroxisome proliferator activated receptor α, acyl‐CoA oxidase, microsomal triglyceride transfer protein, and apolipoprotein B100. Consistent with the significant reduction of hepatic superoxide dismutase activity and marked downregulation of the gene expression of hepatic antioxidant enzymes, the hepatic TBARS level and the plasma level of alanine aminotransferase were only increased in SHR on CD diet. Conclusions: Spontaneously hypertensive rats receiving CD diet showed severe hepatic steatosis associated with reduction of hepatic anti‐oxidant capacity, leading to increased hepatic oxidative stress and tissue damage. Accordingly, hypertension might have a potential effect on the progression of NASH.     

Molecular characterization of the role of orphan receptor small heterodimer partner in development of fatty liver

The orphan receptor Small Heterodimer Partner (SHP, NROB2) regulates metabolic pathways, including hepatic bile acid, lipid, and glucose homeostasis. We reported that SHP-deletion in leptin-deficient OB(-/-) mice increases insulin sensitivity, and prevents the development of fatty liver. The prevention of steatosis in OB(-/-)/SHP(-/-) double mutants is not due to decreased body weight but is associated with increased hepatic very-low-density lipoprotein (VLDL) secretion and elevated microsomal triglyceride transfer protein (MTP) mRNA and protein levels. SHP represses the transactivation of the MTP promoter and the induction of MTP mRNA by LRH-1 in hepatocytes. Adenoviral overexpression of SHP inhibits MTP activity as well as VLDL-apoB protein secretion, and RNAi knockdown of SHP exhibits opposite effects. The expression of SHP in induced in fatty livers of OB(-/-) mice and other genetic or dietary models of steatosis, and acute overexpression of SHP by adenovirus, result in rapid accumulation of neutral lipids in hepatocytes. In addition, the pathways for hepatic lipid uptake and lipogenic program are also downregulated in OB(-/-)/SHP(-/-) mice, which may contribute to the decreased hepatic lipid content. CONCLUSION: These studies demonstrate that SHP regulates the development of fatty liver by modulating hepatic lipid export, uptake, and synthesis, and that the improved peripheral insulin sensitivity in OB(-/-)/SHP(-/-) mice is associated with decreased hepatic steatosis.     

Metformin treatment of rats with diet-induced overweight and hypertriglyceridemia decreases plasma triglyceride concentrations,while decreasing triglyceride and increasing ketone body output by the isolated perfused liver

Metformin has been proposed as a potential drug treatment to reduce liver steatosis. Therefore, the study of the effects of in vivo metformin administration, on hepatic fat metabolism in the isolated perfused liver is of great interest. We have studied the effects of in vivo metformin treatment of rats with experimentally induced overweight, hyperglycemia and hypertriglyceridemia, on plasma hormone and metabolite concentrations, as well as on triglyceride and ketone body output by the isolated perfused livers. Sprague-Dawley rats were fed ad libitum with a high lipid diet for 10 weeks. Then, one rat group was treated for 7 days with 350 mug/kg of BW of metformin per day, whereas the control group received only water. Thereafter, the livers were excised and perfused in vitro under controlled conditions. The hypertriglyceridemic rats had a greater body weight, as well as greater plasma glucose, insulin and triglyceride concentrations, than the control rats fed ordinary chow. In vivo metformin treatment decreased plasma glucose, insulin and triglyceride concentrations. With respect to the overweight, hyperglycemic, hypertriglyceridemic, untreated control rats, the cumulative (i.e. over 3 h of perfusion) triglyceride output by the perfused livers was decreased by >60%, whereas total ketone body (i.e. the sum of 3-hydroxybutyrate and acetoacetate) output was increased by >100% (p < 0.01 for both). In conclusion, the in vivo treatment with metformin of rats with diet-induced overweight and hypertriglyceridemia is capable to re-address hepatic fatty acid metabolism from lipogenesis toward fat oxidation and ketone body production, either directly or through a reduction of insulin concentrations.